436,741 research outputs found
A hard metallic material: Osmium Diboride
We calculate the structural and electronic properties of OsB2 using density
functional theory with or without taking into account spin-orbit (SO)
interaction. Our results show that the bulk modulus with and without SO
interaction are 364 and 365 Gpa respectively, both are in good agreement with
experiment (365-395 Gpa). The evidence of covalent bonding of Os-B, which plays
an important role to form a hard material, is indicated both in charge density,
atoms in molecules analysis, and density of states analysis. The good
metallicity and hardness of OsB2 might suggest its potential application as
hard conductors.Comment: Figures improve
Collective charge fluctuations and Casimir interactions for quasi one-dimensional metals
We investigate the Casimir interaction between two parallel metallic
cylinders and between a metallic cylinder and plate. The material properties of
the metallic objects are implemented by the plasma, Drude and perfect metal
model dielectric functions. We calculate the Casimir interaction numerically at
all separation distances and analytically at large separations. The
large-distance asymptotic interaction between one plasma cylinder parallel to
another plasma cylinder or plate does not depend on the material properties,
but for a Drude cylinder it depends on the dc conductivity . At
intermediate separations, for plasma cylinders the asymptotic interaction
depends on the plasma wave length while for Drude cylinders
the Casimir interaction can become independent of the material properties. We
confirm the analytical results by the numerics and show that at short
separations, the numerical results approach the proximity force approximation
Distribution of minor metallic elements within waste incineration bottom ashes defined by WDX/EDX spectrometry
A number of metallic elements are inherited from waste during thermal treatment and concentrated in the incineration residues. Because the major part of the incineration residue mass are bottom ashes (BAs), their study is of great importance from the point of view of their environmental impact or resource potential. The general focus of this study was on the minor metallic elements present in BAs. They co-occurred with main phases and often determined the inherited potential of the material. The analysed residues were produced from municipal and industrial waste. The BAs were studied using spectroscopic methods of chemical microanalysis: energy dispersive X-ray spectrometry (EDX) and wavelength dispersive X-ray spectrometry (WDX). Both the main and minor metallic elements were concentrated in metallic components. They were typically present as separate grains and metallic inclusions (commonly in the glass matrix of the grains) ranging in size from several to hundreds of micrometres. Despite Fe-, Al- and Cu-rich occurrences, metallic elements rarely occurred in fragments composed of a single element. Their main forms of occurrence were alloy grains, admixtures in polymetallic occurrences and micro-inclusions in glassy matrix. The content of particular elements in those forms was investigated and described in greater detail. Even though two types of bottom ash were formed from different types of waste and differences in used technologies were present, the obtained materials contained metallic components having similar attributes. Elevated concentrations of not only Fe and Al, but also Ti, Cu and Zn, allow us to consider bottom ash as a promising material from the point of view of metallic elements' recovery (e.g. by the physical concentration of elements through gravity or magnetic methods)
Second-harmonic generation in graded metallic films
We study the effective second-harmonic generation (SHG) susceptibility in
graded metallic films by invoking the local field effects exactly, and further
numerically demonstrate that the graded metallic films can serve as a novel
optical material for producing a broad structure in both the linear and SHG
response and an enhancement in the SHG signal.Comment: 10 pages, 2 EPS figures. Minor revision
Phase-change materials handbook
Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided
Material Dependence of the Wire-Particle Casimir Interaction
We study the Casimir interaction between a metallic cylindrical wire and a
metallic spherical particle by employing the scattering formalism. At large
separations, we derive the asymptotic form of the interaction. In addition, we
find the interaction between a metallic wire and an isotropic atom, both in the
non-retarded and retarded limits. We identify the conditions under which the
asymptotic Casimir interaction does not depend on the material properties of
the metallic wire and the particle. Moreover, we compute the exact Casimir
interaction between the particle and the wire numerically. We show that there
is a complete agreement between the numerics and the asymptotic energies at
large separations. For short separations, our numerical results show good
agreement with the proximity force approximation
Coreless Terrestrial Exoplanets
Differentiation in terrestrial planets is expected to include the formation
of a metallic iron core. We predict the existence of terrestrial planets that
have differentiated but have no metallic core--planets that are effectively a
giant silicate mantle. We discuss two paths to forming a coreless terrestrial
planet, whereby the oxidation state during planetary accretion and
solidification will determine the size or existence of any metallic core. Under
this hypothesis, any metallic iron in the bulk accreting material is oxidized
by water, binding the iron in the form of iron oxide into the silicate minerals
of the planetary mantle. The existence of such silicate planets has
consequences for interpreting the compositions and interior density structures
of exoplanets based on their mass and radius measurements.Comment: ApJ, in press. 22 pages, 5 figure
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